How to solve a Magnetic Circuit - part 1

Part 1 - Analysis of magnetic circuits. This video begins with a brief explanation of the specific Maxwell equation (Ampere's Law) that pertains to magnetic circuits. The discussion is center around Prof. Walter Lewin's problem #57 regarding a magnetic loop with an air gap. His problem is easily solved since the viewer is given the permeability value in the core. My treatment here is general and shows the viewer how to determine the permeability of the core material (typically not known beforehand) from the non-linear B-H curve of the magnetic circuit. Prof. Lewin's circuit can be solved analytically because the core permeability is given and no approximation is needed other than assuming there are no fringing fields. How to use B-H curves as well as a brief discussion of what these curves mean with respect to magnetic materials and the terminology used in magnetics is covered. The iterative technique for solution can also be applied to other problems that are non-linear in nature. The analysis of the magnetic circuit using this method is extended to analyze the magnetic circuit as the air gap in the core material is widened from 2.5mm to 10.0mm. Prof. Lewin's video statement of the problem:    • Problem #57 - Electromagnet with Air Gap   Prof. Lewin's solution just published today:    • Solution to Air Gap Problem #57   Enjoy and learn. George Hnatiuk March 22, 2019 10:37am CDT